Keyframe or parent separate meshes in same object?
Yes.

Use vertex groups and armatures.

If an armature can move an attached hand of a human body mesh then it can also move disconnected sub meshes of a Blender Mesh Object.

Parent the mesh to an armature.  Use weight painting if necessary.  Armature need not to be connected. Think of the armature as a collection of controllers and not a mechanism to control an organic mesh model.